The present invention relates to projectors for ophthalmic refracting charts, and specifically to such a projector having a remote control unit which permits selective showing of the refracting chart slides according to a sequence selected by an operator through the remote control.
In the field of ophthalmic refraction, it has been known to use projectors incorporating slides having imaged thereon, the various charts useful to the professional conducting eye examinations. These projector devices represent substantial improvement in patient refraction over the old wall charts long used. Typical of such projectors were the early types having a plurality of slides or targets disposed in a linear relationship and moved back or forth, up or down relative to the projecting light path so as to be selectively positioned on the viewing screen. In these projectors, the selection of slides was done manually, often with difficulty in locating and precisely positioning the desired slide for viewing.
In later instruments, such as illustrated in U.S. Pat. No. 3,655,276 (commonly owned by the assignee of the present invention), the slides were placed on circular discs, which were rotated by a control which might be located remotely from the projector either in an automatic mode or in an incremental mode. In the automatic mode, the slides were sequentially shown, according to their placement on one or more of the slide discs. In the incremental mode, the slides were moved to the next sequential position on a disc. Often multiple discs were provided in the slide magazine and when the first disc had completed a revolution, a second would be picked up and rotated through its positions, and so on until all discs had rotated through the numerous positions. As may be recognized, once a particular slide had been passed, either manually or automatically, the entire sequence might have to be passed to return. Also, the operator would have to step through the slide discs to select a particular one for viewing.
The present invention provides a refracting chart projector having a remote control wherein preferably the entire selection of available slides is viewable on the face of the control in the form of a series of selector buttons, and the operator may select according to this desired sequence the particular slide charts to form the refracting examination.
Other objects, advantages, and features of the invention will become apparent from the following description of the invention as illustrated in the embodiment explained.